The present invention relates to a dustproof cover for covering a guide rail of a linear guide device and, in particular, to an intermediate cover for covering the portion of a guide rail existing between two sliders when a plurality of sliders are provided on the guide rail.
When a linear guide device is assembled into a machine table, in most cases, normally, as shown in FIG. 14, four sliders 2 are mounted on the lower surface of a machine table T. That is, two sliders 2 are assembled onto a guide rail 1 to form one assembly and two other sliders 2 are assembled onto another guide rail 1 to form another assembly, while the two assemblies are fixed onto a machine base D in parallel to each other.
Foreign substances such as welding powder, chips, cutting oil, dust and the like are readily adhere to the linear guide device LG structured in this manner for supporting the machine table T. If such foreign substances are stuck to the guide rail especially to the upper and side surfaces of the guide rail 1, then they penetrate into the interiors of the moving sliders 2. In the interiors of the sliders 2, a large number of rolling members move endlessly while they roll within precisely machined loaded roller rolling passages each consisting of roller rolling grooves 3 formed on the side surfaces of the guide rail 1 and roller rolling grooves (not shown) formed on the inner surfaces of the sliders opposed to the guide rail 1 side surfaces, thereby allowing the sliders 2 to move smoothly. The penetration of the foreign matter into the interiors of the sliders 2 can interfere the smooth rolling movements of the rolling members and thus can worsen the movement precision and the like of not only the sliders 2 but also the machine table T. Therefore, taking proper dustproofing measures in the guide rails is one of the important technical items.
In a conventional guide rail, as means for preventing the guide rail against dust, as shown in FIG. 15, in most cases, bellows 5 and 6 are used. To provide such bellows, Neoprene rubber is coated on the two side surfaces of nylon fiber cloth and further a reinforcing polyester film is adhered to the above to thereby form a sheet. The sheet is folded in a wave form in such a manner that it is freely expandable and contractible, and then two steel plates are respectively mounted to the two ends of the sheet. The bellows 5 respectively provided in the rail end portions are mounted in such a manner that one end of each of the bellows 5 is tapped and fixed to the one end face portion of the guide rail 1 by a screw, while the other end thereof is screwed to the outer end face of the slider 2. On the other hand, the bellows 6, which serves as an intermediate cover for covering the intermediate portion of the guide rail 1 existing between the two sliders 2 and 2, as shown in FIG. 16, is mounted in such a manner that one end thereof is screwed to the inner end face of one slider 2 by a mounting screw 7 while the other end thereof is similarly screwed to the inner end face of the other slider 2 (FIG. 17).
However, in the above-mentioned conventional bellows 6 serving as an intermediate cover, as shown in FIG. 18 in which the bellows portion of FIG. 17 is viewed from below, the lower portions of the bellows are open so that large gaps 8 are formed in continuous waves between the guide rail 1 and the bellows lower portions. That is, foreign substances are can invade the guide rail 1 through these gaps 8.
Also, since the bellows are formed in waves the crown and valley portions thereof to continue with each, the bellows 6 occupies most of a U-shaped space existing between the upper surface 1a and two side surfaces 1b of the guide rail 1 and the upper surface 2a and two side surfaces 2b of the slider 2. This interferes with a space which is necessary to arrange an oil feed pipe for supply of lubricating oil to the linear guide device LG and other attached devices.
Further, when the linear guide device LG is used in such a manner that it is mounted horizontally or vertically on a wall, or when it is used in such a manner that it is mounted to a ceiling upside down, the bellows 6 hangs down so that it cannot protect the guide rail from dust completely, or the bellows 6 can come into contact with other portions of the linear guide device LG.
Moreover, in the conventional bellows, when the end portions thereof are screwed to the slider, as shown in FIG. 16, it is necessary that the mounting screw 7 be inserted into a screw hole 9 formed in the cover end portion from inside of the bellows 6, and it is then threadably engaged into a screw hole formed in the end face of the slider 2, before it is tightened. Thus, the conventional bellows is difficult to mount.
In addition, the bellows is expensive and the durability thereof is not satisfactory.